Process for desulfurization by hydrolysis with metals on charcoal base catalysts



R. B. MASON ETAL 3,367,862 PROCESS FOR DESULFURlZATION BY HYDROLYSISWITH Feb. 6, 1968 METALS ON CHARCOAL BASE CATALYSTS Filed Oct. 18, 1965PQDQONE mokonmm BY 6M PArE/vrxrramn' United States Patent 3,367,862PRUQESS FOR DESULFURHZATIION BY HY- DRQLYSiS WITH METALS 0N CHARCOALBASE CATALYSTS Ralph Burgess Mason, Dcnham Springs, and Glen PorterHammer and Clark Edward Adams, Baton Rouge, La., assignors to EssoResearch and Engineering Company, a corporation of Delaware Filed Oct.18, 1965, Ser. No. 497,411 8 Claims. (Cl. 208-243) ABSTRAT 0F THEDISCLUSURE Process for des-ulfurizing heavy residual fractions bycontacting with water in the presence of a catalyst comprising a metal,metal oxide, or metal sulfide distended on a char base.

This invention relates to a process for the removal of sulfur, nitrogenand metal contaminants from liquid hydrocarbon streams, particularlyheavy petroleum oils. More specifically, the invention relates to thedesulfurization of heavy petroleum oils by hydrolysis in the presence ofcertain metals on charcoal base catalyst employing staged operation.

Generally, sulfur occurs in petroleum stocks in one of the followingforms: mercaptans, sulfides, disulfides, and as part of a more or lesssubstituted ring, of which thiophene, benzothiophene, and dibenzothiophene are the prototypes. The mercaptans are generally found in thelower boiling fractions, e.g. naphtha, kerosene, and light gas oil.Numerous processes for sulfur removal from these lower boiling fractionshave been suggested, such as doctor sweetening (wherein mercaptans areconverted to disulfides), caustic treating, solvent extraction, copperchloride treating, and so forth, all of which give a more or lesssatisfactory decrease in sulfur or inactivation of merc'apt-ans by theirconversion into disulfides. When the process results in the lattereffect, the disulfides generally remain in the treated product and mustbe removed by another step if it is desired to obtain a sulfurfreeproduct.

Sulfur removal from higher boiling fractions, however, has been a muchmore diiiicult operation. Here, the sulfur is present for the most partin the less reactive forms as sulfides, disulfides, and as a part of aring compound, such as substituted thiophenes. Said sulfur, of course,is not susceptible to chemical operations satisfactory for removal ofmercaptans. Extraction processes employing sulfur-selective solvents arealso unsatisfactory because the high boiling fractions contain a muchhigher percentage of sulfur-containing molecules; for example, even if aheavy petroleum oil contains only about 3% sulfur, it is estimated thatsubstantially all the molecules may contain sulfur. Thus, if such aheavy petroleum oil were extracted with a solvent selective to sulfurcompounds, the bulk of the oil would be extracted and lost.

Metallic contaminants, such as nickel and vanadium compounds, are foundas innate constituents in practically all crude oils associated with thehigh Conradson carbon asphaltic and/ or asphal'tenic portion of thecrude. When the crude oil is topped to remove the light fractionsboiling above about 450650 F. the metals are concentrated in theresidual bottoms. The residual botforms may also contain nitrogencompounds. The metals, coke formers and nitrogen compounds, alladversely affect catalysts if the residuum is further treated. When theoil is used as fuel, they also cause poo-r fuel oil performance inindustrial furnaces by forming coke and sludge and by corroding themetal surfaces of the furnace.

It is an object of this invention to provide a process for thepreparation of a low sulfur heavy petroleum oil which is characterizedby a low nitrogen and metals content as well. It is another object ofthis invention to provide a staged process for preparing a fuel oil fromheavy oil which is efiicient and economical.

Briefly, the process of the invention involves contacting a heavypetroleum oil in stages with water and/or water vapor in the presence ofa catalyst comprising certain metals on a charcoal base.

While we do not wish to be bound by any theory, it is postulated thatthe desulfurization and denitrogenation obtained in the followingexamples result from hydrolysis reactions and that the role of thecatalyst is to provide an intimate contact between the feed and thewater molecule involved in the hydrolysis. The hydrophylic nature of thechar support renders it admirably suited to this role.

The invention will be more fully described with reference to theattached drawing which is a flow diagram of one embodiment of theprocess. The heavy oil is initially fed at a temperature of 600-850" F.by lines 1, 2, 3, 4- and 5 to reactors A, B, C and D. After the unitshave been on stream for a time the feed will flow to only two or threeof the reactors because one or two of the reactors will be off streamfor regeneration. Further details regarding regeneration will be givenlater on in this description. Suitable feed stocks include heavy wholecrude oils, atmospheric residuums, vacuum residuums, visbreaker bottoms,deasphalted oils, refinery cycle stocks, and oils derived from oilshale. When required, very viscous oils can be cut back or diluted to asuitable viscosity or gravity with a light diluent oil so that they canbe intimately contacted with water and the catalyts. Oils containing2-10 wt. percent sulfur, preferably 2-6 wt. percent sulfur can beprocessed to yield an oil containing less than 50 wt. percent of thesulfur and nitrogen content of the original process feedstock. Oilswhich have been previously deasphalted can be further reduced in metalscontent to less than 1 ppm. making them suitable stocks for catalyticcracking or they can be used as fuel oil or fuel oil components.

In the embodiment shown in the drawing, reactors A, B, C and D containfixed beds of catalyst with provisions being made to maintain anequilibrium relationship with water vapor. Water or water vapor can beadded by lines 6, 7, 8 or 9. If desired, some or all of the water can beadded with the feed or by wetting the catalyst after regeneration. Thewater content will range from 5-100 wt. percent based on the oil feed.

In another embodiment, not shown, the oil, water and catalyst are workedup into a slurry and the shiny is continuously passed thrcughthereactors. After contacting at the desired conditions for a period, thecatalyst is separated for regeneration and recycle.

The principal feature of the catalyst is the hydrophylic property of thechar support which promotes an intimate contact between the oil and theadsorbed water. Suitable chars are those of high surface area whichresult from pyrolysis of cellulose materials such as wood fibers, cottonfibers, sugars, starches and the nut products of certain plants. Suchpyrolysis results in a dehydration of the cellulose structures. Anothersuitable char is obtained by dehydrochlorination of polyvinylidenechloride polymers (Saran) as disclosed in US. Patent 2,944,031. Charsobtained by low temperature air oxidation of petroleum coke and coal,also, are eminently satisfactory for the catalyst base in this work. Thechar support used in the experiments subsequently discussed is acommercial product known as Columbia Activated Char and it was employedin the form of extrudate pellets of about inch diameter.

Suitable metals are the metals of Groups I, II, VI and VIII of thePeriodic Table. Particularly suitable compounds are those selected fromthe group consisting of Me, MeO and MeS wherein Me is selected from thegroup consisting of nickel, cobalt, copper, iron, zinc, molybdenum,tungsten and mixtures thereof. The most preferred catalysts are charsdeposited with molybdenum, molybdenum oxide, molybdenum sulfide,tungsten oxide, metallic nickel, nickel oxide, nickel sulfide, metalliccopper, copper oxide, metallic cobalt, cobalt oxide, cobalt sulfide,metallic iron, iron oxide and iron sulfide. Mixtures can be used aswell. The metal is preferably present on the char in its highest valencestate. The catalyst can contain from -500 wt. percent metal based on thetotal catalyst.

i char material without the molybdenum oxide and (3) an equivalentamount of molybdenum oxide without the char. In these runs a West Texasdeasphalted oil was employed as feed. This feedstock was prepared bypropane deasphalting a West Texas vacuum residuum bottoms. Thedeasphalted product used in these experiments contained 1.28% sulfur,0.4 wt. percent nitrogen and had an API gravity of 17.6, a Conradsoncarbon value of 4.3 and a metals content of 3 ppm. nickel and 6 ppm.vanadium, respectively. The boiling range of the feed is 950 F. andhigher, predominately 950-1300" F.

For part (1) of the experimental work, 200 grams of a commercialcatalyst containing 10% molybdenum oxide on Columbia Activated Char wascharged to a one-liter The weight ratio of catalyst to oil in a batchsystem stirred Hastalloy autoclave together with 160 grams of rangesfrom 0.25-1 at residence time ranging from 0.5-6 Water so as to wet thecatalyst prior to hydrocarbon conhours. The pressure in the reactors mayvary from 500- tact. Thereupon, 200 grams of the West Texas deasphalt-5000 p.s.i.g. at temperatures in the range of 500-850 ed residuum wasadded and the autoclave was assembled. F. In a flow system, the sametemperature and pressures Traces of air and oxygen were removed byrepeated are desired at oil feed rates of 0.1-1.0 volume pervolpressuring and depressuring with nitrogen. Thcreupon, ume of catalystper hour. the autoclave contents were heated to 690 F. and heldDesulfurized oil from reactor A is passed by line 10 at this temperaturefor two hours. Autogenous pressure to product recovery line 11; however,any desired part of about 3000 p.s.i.g. was developed. of the oil inline 10 can be further treated by diverting it Part (2) of theexperiment was conducted in a similar to reactor B by lines 12 and 3.Similarly, oil recovered by 2 manner with 200 grams of ColumbiaActivated Char conline 13 from reactor B can be recoverey as a productby taining no molybdenum oxide, 165 grams of water and passing it toline 11 or it can be further desulfurized by 190 grams of West Texasdeasphalted oil. Pressure dediverting it to reactor C by lines 14 and 4;also, oil reveloped in this operation was about 2800 p.s.i.g. covered byline 15 from reactor C can be recovered or Part (3) of the experimentwas conducted in a simifurther treated in reactor D employing lines 16and 5. lar manner except that the desulfurizing agent consisted Oilrecovered from reactor D by line 18 can be passed of 20 grams ofmolybdenum trioxide with no added char to reactor A for furthertreatment or it can be recovmaterial. The charge also consisted of 165grams of waered as a product by lines 17 and 11. ter and 188 grams ofthe West Texas deasphalted feed.

Periodically each of reactors A, B, C and D are taken Maximumtemperature in this two hour operation was off stream for regenerationof the catalyst. Fixed bed 710 F. and the autogenic pressure was 2300p.s.i.g. reactors are preferably regenerated by burning with air. Theresults of this study showing superior perform- Air is supplied by lines10, 20, 21 and Z2. ance for the molybdenum oxide-char support, but ap-The valves and bypass lines employed for bypassing a preciabledesulfurization with the char alone, and almost reactor which is beingregenerated have not been shown. negligible desulfurization with themolybdenum trioxide The technique of regenerating reactors in a stagedseries alone, are tabulated below.

TABLE I 10% M003 on Activated Molybdenum Catalyst Feed Activated CarbonTricxidc Carbon Treating Temp, F 600 690 710 Wt. percent water on feed(liquid product inspecso 90 90 17.6 29. o 24. 2 16. 7 Sulfur,Wt.Pcrcent 1. 28 0.26 0.62 1.2 Percent Sulfur Removal 75 6 PercentNitrogen Removal 75 Conradson Carbon, Pcrcent. 4. 3 O. 44 Nickel, p.p.m3 0 Vanadium, p.p.m 6 0 is well known to those skilled in the art. In athree stage, four reactor system like that shown in the drawing, thesequence of operation is as follows:

The catalyst in the reactor of position 4 is undergoing regeneration.

EXAMPLE 1 The runs herein disclosed are designed to show a su periororder of desulfurization by hydrolysis in presence of char supports. Tothis end experiments were made with (1) molybdenum oxide-char catalyst(2) the same The superiority of the molybdena-char catalyst over thesame char but without the sulfur acceptor is demonstrated.

EXAMPLE 2 An experiment similar to part 1) of the foregoing work wasconducted with a 75% shale oil distillate which contained 0.71% sulfurand 2.4% nitrogen. In this work, 200 grams of catalyst comprising 10%molybdenum trioxide on Columbia Activ-ated Char was contacted with gramsof water and then 210 grams of the shale oil distillate. After purgingthe air the charge was heated to 680 F. for one hour at an autogenicpressure of about 3000 p.s.i.g. Liquid product recovered had an APIgravity of 29.0, sulfur content of 0.5 and nitrogen content of 1.1. Thiscorresponds to 26% to 56% nitrogen and sulfur removal, respectively.

EXAMPLE 3 The foregoing Examples 1 and 2 were with dififerentfeedstocks. A further study of the feedstock variable is given in theinstant example. In this run, 200 grams of catalyst which comprisedmolybdenum trioxide on Columbia Activated Char was contacted with 160grams of water and then with 204 grams of Kuwait vacuum residuum. Thisfeedstock contained 5.9% sulfur. The composite charge, after purging theair, was heated to 675 F. for two hours in which the autogenic pressurewas 2500 p.s.i.g. The product contained 4.6% sulfur which corresponds to22% desulfuriz-ation.

EXAMPLE 4 Examples l-3 have shown a good degree of desulfuri zation whenmolybdenum oxide char catalyst was employed. This example demonstratesthat the molybdenum sulfide-char support is active in thisdesulfurization system and that loss in activity from sulfiding theoxide is not a limitation to the process. For this run 205 grams ofmolybdenum sulfide-char catalyst, prepared by contacting the oxide formwith a hydrogen-hydrogen sulfide gas at 700 F., was contacted with 160grams of water and 190 grams of the deasphalted oil used in Example 1.After expelling the air, the charge was heated for 2.5 hours at 705 F.,in which the autogenic pressure was 3250 p.s.i.g. The satisfactoryperformance of the sulfide catalyst is shown by comparison with theresults of Experiment 1 as follows:

TABLE H Data Source Inspections Feed Experiment 1 Experiment (Part 1) 4Gravity 17. 6 29.0 30. 0

Sulfur 1. 28 0.26 0.23

Sulfur Removal, Wt. percent 70 82 EXAMPLE 5 pholted oil by hydrolysismolybdenum sulfide-activated char catalyst 50 wt. percent water on oilfeed Temperature, F. 650 Pressure, p.s.i.g 400 Oil feed rate, v./v./hr.0.5 Volumes of oil/vol. cat. at end of period Wt. percent sulfur removal16 Wt. percent nitrogen removal EXAMPLE 6 In a further study of theeffect of pressure, the flow unit was operated with the molybdenumtrioxide char catalyst, 50% water on oil feed, and West Texasdeasphalted oil at 2500 p.s.i.g. and 700 F. until 7 volumes of feed hadcontacted the catalyst at an oil rate of 0.5

v./v./hr. These conditions provide an average residence time of lessthan one hour. The desulfurization and the denitrogenation at the end ofthis operation was 24% and 40%, respectively. These results show clearlythat the performance is not solely adsorption on the catalyst andfurther improvements with residence times greater than one hour arevisualized.

The foregoing description and examples clearly demonstrate the value ofchar base catalysts in association with adsorbed water for thedesulfurization and denitrogenation of high sulfur heavy petroleum oils.

What is claimed is:

1. A process for the desulfurization of a high sulfur petroleum oilcomprising contacting the oil at elevated temperature and pressure witha treating agent consisting of 5-100 wt. percent water based on the oilin the presence of a catalyst comprising a material selected from thegroup consisting of Me, MeO and MeS wherein Me is selected from thegroup consisting of metals of Group I, Group II, Group VI and Group VIIIof the Periodic Table deposited on a char support.

2. Process according to claim 1 in which the temperature ranges from500-850 F. and the pressure ranges from 500-5000 p.s.i.g.

3. Process according to claim 1 in which MeO is molybdenum oxide.

4. Process according to claim 1 in which a plurality of reactors arearranged to provide staged contacting.

5. Process according to claim 1 in which the catalyst is maintained in afixed bed.

6. Process according to claim 1 in which the oil, water and catalyst aremixed together to form a slurry and are then passed through a pluralityof staged reactors.

7. A process for the desulfurization of a petroleum residuum containing2-10 wt. percent sulfur, nitrogen compounds and metal compoundscomprising contacting theoil in stages at a temperature ranging from500-850" F. and a pressure ranging from 500-5000 p.s.i.g. with atreating agent consisting of 5-100 wt. percent water in the presence ofa catalyst comprising a material selected from the group consisting ofmolybdenum, tungsten, nickel, copper, cobalt and iron and oxides andsulfides thereof deposited on a char support.

8. A process for the removal of sulfur, nitrogen and metals for oilderived from oil shale comprising contacting the oil in stages at atemperature ranging from $00- 850 F. and a pressure ranging from500-5000 p.s.i.g. with a treating agent consisting of 5-100 wt. percentwater in the presence of a catalyst comprising a material selected fromthe group consisting of molybdenum, tungsten, nickel, copper, cobalt andiron and oxides and sulfides thereof deposited on a char support.

References Cited UNITED STATES PATENTS 2,901,423 8/1959 Herbert et al.208--264 SAMUEL P. JONES, Primary Examiner.

